1. Field of the Invention
The present invention relates to an analytical apparatus that forms and analyzes the hydrides of target components contained in a sample.
2. Description of the Related Art
Atomic absorption and ICP atomic emission analysis techniques are widely used in analytic chemistry laboratories for measuring the concentrations of various elements in a sample. One preferred procedure for performing this analysis is to first decompose the sample into gas phase hydrides then atomize these hydrides in the detecting part of an atomic absorption or ICP atomic emission apparatus, and finally measure the concentrations of selected elements from the sample. Converting the original sample into gas phase hydrides make the target elements much easier to atomize and detect by atomic absorption/emission techniques.
The hydrides are formed preferably by adding acids and reducing agents to the samples. The types and concentrations of acids and reducing agents used to form the hydrides depend upon the elements that are analyzed. Unfortunately, selecting the types and concentrations of the hydride forming agents has, up to now, been a time consuming, manual operation. Every time a new element was measured in a sample, manual adjustments had to be made to the types and concentrations of hydride forming agents.
The concentration of an element from a sample is measured by comparing the spectral intensity of an atomic absorption or emission line with the intensity of that same line from a standard that contains a known concentration of the same element. The intensities of the atomic absorption/emission line are plotted as a function of the concentration of the standard, and the resulting curve of intensity vs. elemental concentration is called the analytical curve.
When the concentration of an element in a sample is too high or too low to fall within the upper and lower concentration limits of the analytical curve, the measurement must be repeated under different hydride formation conditions. Up to now, these adjustments were made by hand by the operator of the apparatus.
Further, conventional apparatuses employ mainly a continuous suction method, a batch addition method and an FIA method (loop injection method) as methods for introducing samples. The continuous suction method requires a lot (at least about 20 ml) of sample liquids, and therefore the concentration rate is restricted, which in turn restricts analysis of trace amounts. The batch addition method makes use of an air segment system, and therefore the sample liquids remain in the tube line to allow the memory to remain. Accordingly, the tube line has to be washed every measurement.